The narcotic antagonist, naltrexone, will be used for the treatment of opiate-dependent individuals in two settings. One will involve an open clinical trial to determine the acceptability of the treatment to a group largely composed of persons recently detoxified from opiates and the feasibility of this approach to treatment on a chronic basis. Observations will be made of the side effects, precautions or contraindications to such treatment, as well as its general efficacy. The second setting will be rather unusual in that it will involve the use of the drug under conditions of a controlled clinical trial in a group of persons considered to be at high risk for recidivism. These will be persons who have completed treatment on a "drug-free" ward using a therapeutic community approach and who are about to re-enter the outside community. Treatment will be on a time-limited basis, the specific objective being to determine whether this type of use of a narcotic antagonist will reduce recidivism rates, as well as facilitating an easier entry back into the straight world. Eventually, during the life of the study, we should hope to have available long-acting depot preparations of naltrexone to use in both types of individuals.